William f



Reissuecl July 18, 1950 PREPARATION OF SUBSTITUTED ALKYLOLTETRAHYDROPYRAN William F. Gresham and William E. Grigsby, Wilmington, DeL, assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a cornotation of Delaware Original No. 2,493,964, dated Jan- No Drawing.

nary 10, 1950, Serial No. 782,030, October 24,

1947. Serial No. 157,191

8 Claims.

Application for reissue April 20, 1950,

Matter enclosed in heavy brackets II appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue This invention relates to a process for preparation of tetrahydropyrans, and more particularly to the preparation of alkylol substituted tetrahydropyrans from an aldehyde and a 1,3-diene.

One object of the invention is to provide a process for the preparation of new compositions of matter. Another object is to provide a process for the preparation of alkylol substituted hydroxy tetrahydropyrans by the interaction of an aldehyde with a 1,3-diene and especially butadiene. Still another obj ect is to provide a process for the preparation of alkylol substituted hydroxy tetrahydropyrans by the reaction of formaldehyde with butadiene. Yet another object is to provide conditions for effecting the reaction while at one and the same time inhibiting the polymerization of the butadiene. Other objects and advantages of the invention will hereinafter appear.

The above and other objects are accomplished by reacting an aldehyde such as formaldehyde with a 1,3-diene such as butadiene in the presence of an acid condensation catalyst and a polymerization inhibitor. These algylol and formal substituted tetrahydropyrans are obtained from formaldehyde and butadiene[s.]:

[(1) 3 hydroxy 4 methyloltetrahydropyran and (2) its formal:

CHCHIOH 4 CH 5 3 CHOH on. 1 cm te med;

[(3)] 4 hydroxy-3-methyloltetrahydropyran and [(4)] its formal:

OBOE 0 on,

on O

4 CH 5 3 HI having a boiling point of 142 C. Inasmuch as this intermediate can be reconverted to the desired product, it can be recycled and by this means the desired product produced in the substantial absence of these intermediates.

Examples are given describing the preferred embodiments of the invention in which parts are by weight unless otherwise stated.

Example 1.-A charge of 134.4 grams H2O, 3.8 grams H2804, 0.2 gram hydroquinone, 40.8 grams paraformaldehyde and 24 grams butadiene was processed in a 325 ml. silver-lined shaker tube at 121-135/4 hrs., during which time the autogenous pressure fell from 250.20 p. s. i. the discharge (200.4 grams, light brown liquid) contained 17.5% of the charged CHzO, of which amount 71% was recovered in the distillate. The discharge was carefully neutralized with NaOI-l and distilled. The first cut (85-100, 182.4 grams) contained an upper layer of 6 cc. of intermediate products including ll-vinyl dioxane-LE. The next cut was the formal of [3-hydroxy-4-methyloltetrahydropyran,] 4 hydrozcy-JB-methyloltetrahydropyran, 18.6 grams. This substance boils at 79/1'0 mm. or 56/2 mm., has a refractive index (as a, supercooled liquid) of 1.4668 at 25 C. It is a crystalline, Water-soluble solid, melting at 55 (ex ether or cyciohexane) The remainder, 18.6 g., boiled at 98-124 C. at 1 mm. pressure. Redistillation of this fraction gave a pure compound boiling at 120 C./1 mm. This glycol is a viscous, water-soluble, nearly colorless oil with a refractive index of 1.4863 at The residue was 9.7 g. or 3.7 g. net (allowing for NazSOr).

4 unchanged formal and 11.1 g. of [3-hydroxy-4- methyloltetrahydropyran] 4 hydromy-Zi-mthyloltetrahydropymn.

Example 5.A 37 g. fraction boiling below 115 C./1 mm. and a 20.3 g. fraction boiling higher than what was believed to be [3-hydroxy-4-methyloltetrahydropyran] 4-hydroxy-3-methyloltetra- [Formal of ta'Hydmn 3-Hydroxy 4'methylol' 4-methyloltetmbydm' tetrahydrw pymn] py .l 'orma of Water Insoljgg g i 4-Hydroc1 uble Layer Wang?! S-mcflwlol- Considered Total n tetrahvdroas A-3- purcn Dihydropyrsn Per cent Per cent Per cent Per cent Conv. (based on O4H). 31.1 20.1 10.1 76.9 Yield (based on consumed CHnO)- 26. 4 36.4 0. 7 71.5

Example 2.The aqueous fraction from Example 1, including the upper layer, was recycled with make-up CHaO, H2804, hydroquinone, and butadiene under the same conditions (121-125/4 hrs./32059 p. s. i.) Unconverted formaldehyde amounted to 25.6%. The product was analyzed as described in Example 1. The upper layer of the aqueous distillate was 16 cc. (an increase of hudropymn (B. P. ca. 120 (1/1 mm.) was boiled at atmospheric pressure with 155.4 g. of water and 10.8 g. of H2804 for 7.5 hours. Neutralization of the H2804 with caustic and distillation gave 20.0 g. of [3 hydroxy 4 methyloltetrahydropyran] 4-hydromy-3-1nethyloltetrahydropymn. (Either isomerization or/and hydrolysis of formals occurred yielding the above compound.)

10 cc. over the charged amount). Example 6.--A mixture comprising 202.5 g. H20,

Formal o! r v m i-methyioltatrahydro- 0 an] tetrahydropyra Formal of Water Insoi- .i-Hmirozv uble Layer mmhydrm 8-methylo1- Considered Total ran tetrahvdrcas A-3- pvran Dihydropyran Per cent Per cent Per cent Per cent Conv. (based on 04H) 23. 0 30. 3 2B. 8 86.1 Yield (based on consumed CHi0)- 21. 3 50.3 12. 4 84.0

Example 3.--The aqueous distillate containing 8.8 g. conc. H01, 0.3 g. hydroquinone, 62.1 g. para- 16 cc. of upper layer obtained in Example 2 was processed with make-up formaldehyde (12.7 g.) and 4.4 g. of H2804 in the absence of butadiene at 160-163 C. for 1 hour. Distillation of the formaldehyde, and 27 g. butadiene was processed at 123-13073 hrs/410450 p. s. i. (autogeneous pressure). The product was analyzed as described in Example 1.

[3-Hydroxy ggfigfg 4-methyio1- 4 memylo tetrehydrotetrahydro DY pymn] Formal of Water Insolf i-Hydrocy uble Layer mm am S-mcthulol- Considered Total Z Ietmhydroas A-3- p purcn Dihydropyran Per cent Per cent Per cent Per cent Conv. (based on C He) 25. 1 42. 5 7. 2 74. 8 Yield (based on consumed C11 0) i7. 3 43. 8 2. 5 63. 6

product, after neutralization of the H2804 with aqueous caustic, gave 6.8 g. of the formal of [3-hydroxy-4 methyloltetrahydropyran] 4 hydroxy-3-methyloltetrahydropyran and 14 g, of [ZS-hydroxy 4 methyioltetrahydropyran] 4-hydroxy-3-methyloltetrahydropyran.

Example 4.-A reaction mixture comprising 20.0 g. of the formal of [3-hydroxy-4-methyloltetrahydropyran] 4 hydr0xy-3 methyloltetrahydropymn, 275.7 g. of water and 5.0 g. of H2304 was processed at 122-134/0. for 2 hours. Neutraliza- Example 7.A mixture consisting of 116.6 g. acetic acid, 3.5 g. H2304, 0.2 g. hydroquinone, 24 g. butadiene, 42.0 g. paraformaldehyde, 26.2 g. H2O was processed at 118-125/4 hrs. Titration of the discharge showed that 7% of the CHzO was unconverted. Enough NaOH was added (3 g.) to neutralize the H2804 and the Water and acetic acid were removed by distillation. The first cut was 28.1 g. of the solid formal of [3-hydroxy-4-rnethyloltetrahydropyran] 4-hydroxy-3- methyloltetmhydropyran. The second out, 5.3 g.,

tion and distillation of the product gave 3.3 g. or boiled from 61/1,5 mm. to 96.5/1.5 mm., while the next fraction, 4.9 g., had a boiling range of 98.5-1011/l.5 mm., and a refractive index (25") of 1.4618. The final cut, B. P. 107-140/1.5 mm. Weighed 10.5 g. The net residue Was 3 g. The formal was produced in 44% conversion (based on C4Hs) and 47.3% yield (based on CH44O consumed). The higher boiling fractions are esters and are assumed to contain the monoand diacetates of [3-hydroxy-4-methyloltetrahydropyran] 4-hydrory-3-methyloltetrahydropymn.

This example illustrates, inter alia, that when an organic acid such as acetic acid is used as a diluent in place of water, esters are obtained as well as the cyclic formal. Upon analysis the properties of the products were found to be as follows:

Properties Any suitable acid condensation catalyst may be employed such, for example, as hydrochloric acid, phosphoric acid. boron triiiuoride (either alone or as a complex with water or aldehyde), aromatic sulionic acids, or other strongly acid condensation catalysts. The catalysts should be employed in concentrations equivalent to the concentration of sulfuric acid when it is used, 1. e., concentrations between 0.5 and 0% of the total charge. and optimum ratios from 1.25 to 2% of sulfuric acid.

Any suitable form of formaldehyde may be used such, for example, as 37% aqueous formaldehyde (known commercially as Formalin). paraformaldehyde, or trioxane. Polymerization Found Cele.

[3 -Hydroxy-4-methyloltetrahydropyran (or an ISOmBl' Z 4-Hud)rn:ty -msth1I1oltetrcM/dropymn (or an isomer Odorless. colorless oil- Boiling point 1290/1 mm np Solubility Viscosity at 100 F D1 Molecular refraction" Percent 0 Percent H. Hydroxyl number 85 Adjacent hydroxyl groups, m. eq./2 g. 2 [Formal of 3-l1ydroxy-i-methyloltetrahydropyren (or an isomer) Formal of 4-12udmxy-s-mcthyloltetmhzldropymn (or an isomer):

Colorless. almost odorless solidsolvents.

aq. KgC 0; worganic Generally speaking. the afore-illustrated reactions ma be conducted at temperatures between 100 and 200 C. with an optimum range between 120 and 130 C. A higher temperature tends to give greater tar formation and wider byproduct distribution. The reaction is conducted at these temperatures for processing times ranging from 15 minutes (at 150 C.) to 6 hours (at 120 0.); a four-hour reaction time gave purer [3-hydroxy-4-methyloltetrahydropyran] 4-hydrowy-3-methyloltetrahydropyran.

The ratio of formaldehyde to butadiene may range from 1 to 6 moles of formaldehyde per mole of butadiene, although the optimum is 3 or more moles formaldehyde per mole of the butadiene. The formaldehyde concentrations should range between 10 and of the total charge with optimum concentrations between 15 and 25%.

Other aldehydes may be used such as acetaldehyde, propanal, the butanals, and the higher straight and branched chain aldehydes. These aldehydes, as well as formaldehyde may be reacted, (in accord with the invention with the proportions and operational procedures used for the formaldehyde-butadiene reaction) with 1.3- dienes other than butadiene such as. Z-methyl. 1.3-butadiene, z-ethyl 1,3-butadiene and the like.

inhibitors otherlfs] than hydroquinone may, likewise, be used, examples of which are pyrogallol, catechol, t-butyl catechol, etc.

Because the material boiling higher than the formal of [3-hydroxy-4-methyloltetrahydropyran] 4-hydro:cy-3-methyloltetrahydropymn contains primarily a compound boiling at C./1 mm., and because from theoretical considerations, isomers should be formed, this fraction is considered to be [3-hydroxy-4-methyloltetrahydropyran] 4-hydr093y-3-methyloltetmhydlropyran in the calculation of yield data. These calculations are, it appears, wholly justified since materials boiling lower and higher than 120 C./1 mm. are converted to 4-hydrozcy-3-methyloltetrahrrdropyran by processing with aqueous sulfuric acid. (See Example 5.)

The compounds prepared are valuable intermediates for use in the preparation of plasticizers and other compounds.

[The product of the examples of S-hydroxy- 4-methyloltetrahydropyran and/or 4-hydroxy-3- methyloltetrahydropyran and/or stereoisomers thereof and in the claims will be referred to as B-hydroxy-4-methyloltetrahydropyran.]

We claim:

1. [In a] A process for the preparation of alkylol-substituted hydroxytetrahydropyrans, their 7 cyclic formals and 4-vinyl-L3-dioxane which comprises reacting at least one moi of formaldehyde per mol of butadiene in the presence of a polymerization inhibitor and an acidic condensation catalyst at a temperature between 100 and 200 C. and under autogenous pressure.

2. The process of claim I conducted with a ratio of from 1 to 6 moles of formaldehyde per mole of butadiene.

3. The process of claim 1 in which from to 40% of formaldehyde is used based on the total charge.

4. A process for the preparation of [ii-hydroxy-4-methyloltetrahydropyran] 4-hydroxy-3- methyloltetmhydropyran which comprises reactin; from one to six mols of formaldehyde per mol of butadlene in the presence of water, a polymerization inhibitor and an acidic condensation catalyst at a temperature between 100 and 200 0., neutralizing the catalyst and recovering the [3-hydroxy-4-methyloltetrahydropyran] 4-hydreary-3-methyl0ltetrahydropyran after distilling off the formal of [3-hydroxy-4-methyloltetrahydropyran] 4-hydr0xy-3-methyloltetrahydropyran.

5. A process for the preparation of the formal of [3-hydroxy-4-methyloltetrahydropyran] 4- hydroxy-Ii-methyloltetrahydropyran which comprises reacting from one to six mols of formaldehyde per mOl of butadiene in the presence of water, a polymerization inhibitor and an acidic condensation catalyst at a temperature between 100 and 200 0., neutralizing the catalyst and recovering the formal of [3-hydroxy-4-methyloltetrahydropyran] 4-hydroxy-3-methyloltetrahildropyran by distillation.

6. A process for the preparation of 4-vinyl-l,3- dioxane which comprises reacting from 1 to 6 mole of formaldehyde per mol of butadiene in the presence of a polymerization inhibitor and an acidic condensation catalyst at a temperature between 100 and 200 0., neutralizing the catalyst and separating from a distillation out between 85 and 100 C. the 4-vinyl-l,3-dioxane.

[7. 4-vinyl-l,3-dioxane.]

[8. An alkylol substituted tetrahydropyran, produced by reacting formaldehyde with butadiene in the presence of water, a polymerization inhibitor and an acidic condensation catalyst at a, temperature between 100 and 200 C., boiling at 290-291 C. and 760 mm., having a specific gravity of 1.175 and a refractive index at 25 C. of 1.4867] [9. A formal substituted tetrahydropyran, obtained by reacting formaldehyde with butadiene in the presence of water, a polymerization inhibitor and an acidic condensation catalyst at a temperature between 100 and 200 (3., having a melting point of C., a boiling point of 79 C. at 10 mm., and a refractive index of 1.4668 at 25 0.]

10. The product, 4-hydrory-3-methyloltetrahydropyran, having approximately these properties: boiling at 290291 C. at 760 mm., having a specific gravity of 1.175 at 25 C. and a refractive index at 25 C. of 1.4867.

11. The formal of 4-hydroxy-3-methyloltet1ahydropyran, having approximately these properties: a melting point of 55 0., a boiling point of 79 C. at 10 mm., a refractive index (as a supercooled liquid) of 1.4668 at 25 C. and the formula:

CH cm CH: CH:

WILLIAM F. GRESHAM. WILLIAM E. GRIGSBY.

REFERENCES CITED The following references are of record in the file of this patent or the original patent:

UNITED STATES PATENTS Number Name Date 2,362,307 Ritter Nov, 7, 1944 2,421,862 Arundale June 10, 1947 Certificate of Correction Reissue No, 23,248 July 18, 1950 YVILLIAINI F. GRESHAh/I ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 24, for elgylol" read alkylol column 2, line 31, for 25020 read 250-20 column 3, line 74, for 122134/C. rend 122134 C.

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 17th day of October, A. D. 1950.

THOMAS F. MURPHY,

Assistant Uommiss'ioner of Patents. 

